Sound effect devices of electronic musical instruments can be divided into analog circuit sound effect devices and digital circuit sound effect devices according to the forms of internal circuits. The analog circuit sound effect devices only provide one kind of or limited kinds of sound effects and functions, and thus are limited to a certain degree of use. The digital circuit sound effect devices can be used for selecting sound effects and functions within a specified range.
Some classic sound effect devices have been upgraded by manufacturers or have been out of production, so the classic sound effects of different eras and different versions are difficult to reproduce. Generally, the sound effect types and functions of the digital circuit sound effect devices are fixed. More specifically, the software of the digital circuit sound effect devices is matched with hardware, and cannot be changed at any time or randomly. Accordingly, the sound effects and the functions realized by the sound effect devices in the traditional sense are fixed. For example, an overdrive simulating sound effect device can only realize the sound effect of overdrive, but cannot produce the sound effect of reverberation. Different sound effect devices are needed in every performance for different performance styles, performance settings, and different player preferences. In this case, players need to carry multiple sound effect devices, so it is very inconvenient.